Expansion valve and refrigerating system

ABSTRACT

An expansion valve comprises an orifice formed in a valve body and a valve member fixed to a movable member. Movement of a diaphragm is transmitted to an actuating rod via a member and the actuating rod actuated the movable member to control the opening amount of the path between the valve member and the orifice. An orifice member affixed to the orifice is made of a material harder than the valve body, and free from erosion or other damage by a refrigerant, which will otherwise occur at the valve opening portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an expansion valve and a refrigerating systemfor use in an air conditioner of a car, refrigerating display case, orthe like.

2. Description of the Prior Art

FIG. 6 shows a cooling cycle of an air conditioner of a car. The coolingcycle 50 comprises a compressor 51 driven by an engine (not shown) via aclutch, condenser 52 for cooling and condensing a gaseous refrigerantheated and compressed by the compressor 51, liquid tank 53 forseparating the refrigerant condensed by the condenser 52 into vapor andliquid and for removing moisture and dust from the refrigerant,expansion valve 54 for expanding the refrigerant from the liquid tank53, and evaporator 55 for heat-exchange between air and the refrigerantto cool the air to be blown into the compartment, which all areconnected by a pipe network.

Typically used as the expansion valve 54 in the refrigerating cycle isone of an internal pressure-equalizing type disclosed by Japanese PatentLaid-Open Publication Sho 51-86852, which includes a pressurizingchamber and a pressure-equalizing chamber which are separated into upperand lower divisions by a diaphragm, the pressure-equalizing chamberbeing communicated with the inner space of the main body through apressure-equalizing path.

R11 (CCl₃ F), R12 (CCl₂ F₂) and other conventional flongroup materialshad been used as refrigerants for cooling or refrigerating systems ofthe type referred to above. However, these materials in which allhydrogen atoms of hydrocarbon radicals have been replaced bychlorine-containing halogen are subject to a worldwide restraint to stopthe destruction of the ozone layer in the stratosphere. To providealternate flon-group refrigerants that will not destruct the ozonelayer, hydrogen-containing halogenated hydrocarbon refrigerants, such asR22 (CHClF₂), R123 (CF₃ CHCl₂), R111b (CCl₂ FCH₃), R131a (CF₃ CH₂ F),and R152a (COOF₂ CH₃), have been developed. Among them, non-chlorinatedhalogenated hydrocarbon, such as R134a (CF₃ CH₂ F) and R152a (CHF₂ CH₃),are considered hopeful.

Non-chlorinated halogenated hydrocarbon, however, is inferior toconventional flon-group refrigerants in respect of lubricity, and oftencauses metallic powder to mix in the refrigerant.

Since the expansion valve, among various elements of a refrigeratingcycle, comprises a valve member opening and shutting an orifice, thevalve seat of the orifice is subject to local abrasion or a sort ofcorrosion called erosion by metallic powder or other particles containedin the refrigerant.

Japanese Patent Laid-Open Publication Hei 5-346276 discloses aconstruction in which a guide member made of SUS is slidably disposed inan orifice portion of a valve body made of brass to guide an actuatingrod for operating the valve.

OBJECT OF THE INVENTION

It is therefore an object of the invention to provide an expansion valveand a refrigerating cycle free from the drawbacks discussed above.

SUMMARY OF THE INVENTION

According to the invention, there is provided an expansion valvecomprising a cylindrical orifice member which is made of a metallicmaterial having a larger hardness than a valve body and is fixed at avalve opening to behave as a valve seat for contact with a valve member.

A tip end of the valve member moves into and away from contact with thevalve seat at the valve opening to shut and open the valve. The valveseat made of the hard material is protected against corrosion such aserosion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of the entire structure ofan internal pressure-equalizing expansion valve according to theinvention;

FIG. 2 is a fragmentary cross-sectional view showing a an orifice memberand surrounding members according to a first embodiment of the inventionin an enlarged scale;

FIG. 3 is a fragmentary cross-sectional view showing a part of theorifice member according to the first embodiment of the invention;

FIG. 4 is a fragmentary cross-sectional view of a part of an orificemember according to a second embodiment of the invention;

FIG. 5 is a fragmentary cross-sectional view of an orifice memberaccording to a third embodiment of the invention;

FIG. 6 is a schematic view showing the entire arrangement of arefrigerating system;

FIG. 7 is a cross-sectional view of an expansion valve according to afurther embodiment of the invention;

FIG. 8 is a fragmentary view showing a part of the structure of FIG. 7in an enlarged scale;

FIG. 9 is a cross-sectional view of an expansion valve according to afurther embodiment of the invention;

FIG. 10 is a fragmentary view showing a part of the structure of FIG. 9in an enlarged scale;

FIG. 11 is a cross-sectional view of an expansion valve according to afurther embodiment of the invention;

FIG. 12 is a fragmentary view showing a part of the structure of FIG. 11in an enlarged scale; and

FIG. 13 is a perspective view of an orifice member according to afurther embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Explained below are some embodiments of the invention with reference tothe drawings.

An internal pressure-equalizing expansion valve shown in FIG. 1comprises a valve portion A for decreasing the pressure of a highlypressurized liquid refrigerant, and a power element portion B which is adriving portion for controlling the opening rate of the valve portion A.

The power element portion B includes a power element outer shell 3comprising an upper cover portion 1 and a lower support portion 2(diaphragm receiver), and a diaphragm 4 sandwiched and welded betweenouter circumferential edges of the upper cover portion 1 and the lowersupport portion 2. The diaphragm 4 divide an interior space in the powerelement outer shell 3 into upper and lower chambers, namely, apressurizing chamber 5 and a pressure-equalizing chamber 6, and thepressurizing chamber 5 communicates with the interior of aheat-sensitive cylinder 8 through a conduit 7.

The heat-sensitive cylinder 8 is provided at an exit portion of anevaporator (not shown) to detect the temperature of the refrigerant nearthe exit of the evaporator, then convert the temperature into a pressureand recognize it as the pressure of the power element space(pressurizing chamber 5). The pressure, when increased, behaves as theforce for pressing the diaphragm 4 downwardly and moving the valvemember 9 in its opening direction.

The valve portion A comprises a valve body 10 made of brass and havingan inlet 11 for introducing a refrigerant of a high pressure, an outlet12 for letting out the refrigerant of a low pressure, a valve opening 30and a valve chamber 13 communicating the inlet 11 with the outlet 12.Formed in the valve body 10 as an outer shell is a pressure-equalizingpath 14 for communicating the valve chamber 13 with thepressure-equalizing chamber 6.

The valve body 10 includes a hitching member 15 which is attached to thelower threaded end by screw engagement. Assembled to and in the valvebody 10 are a movement regulating member 16 which cooperates with thediaphragm 4 to regulate downward movements of the diaphragm 4; actuatingrods 17 for transmitting the displacement of the diaphragm 4 to thelower mechanism (although only one actuating rod is illustrated, threeare provided at predetermined intervals in the circumferential directionof a valve mover 18 to move vertically in three vertical holes formed inthe valve body 10); a valve member 9 brought into contact with or awayfrom a valve seat on an orifice member 100 formed at the aperture of theorifice 30 (illustrated in the form of a needle valve supported on thevalve mover 18); a biasing spring 20 which energizes the valve member 9upwardly (toward the valve seat); and a adjusting member 21 foradjusting the biasing force of the spring 20.

The adjusting member 21 is a polygonal nut, e.g. a hexagon nut, which isslidably received in the inner polygonal hole of the hitching member 15and engages with an adjusting bolt 22 by screw engagement to move up anddown in response to a rotation of the adjusting bolt 22. The adjustingbolt 22 has a polygonal lower end 22a to be rotated for adjustment, androtatably received in the hitching member 15 through the seal of anO-ring 23 such that the lower end 22a projects downwardly from the lowerend of the hitching member 15.

The hitching member 15 has a threaded open end with which a protectivecap 25 having a seal packing 24 on its inner circumferential surface isremovably attached such that an operator can rotate the adjusting bolt22 by removing the protective cap 25.

The present invention particularly uses an orifice member 100 secured inthe orifice 30 of the expansion valve constructed as explained above.

FIG. 2 shows the orifice member 100 secured in the orifice 30. Theorifice member 100 is made of a metallic material harder than thematerial of the valve body 10. More specifically, if the valve body 10is made of brass, then the orifice member 100 is made of stainlesssteel. The valve member 9 is also made of stainless steel.

FIG. 3 shows an embodiment in which the orifice member 100 is secured tothe valve body 10 by press fit.

The orifice member 100 is cylindrical and the diameter of its outercircumferential surface 106 is slightly larger than the inner diameterof the hole formed in the valve body 10 to receive the orifice member100.

As stated above, the valve body 10 is made of brass, for example, andthe orifice member 100 is made of stainless steel. Therefore, by pressfitting the orifice member 100 having a higher hardness in the valvebody 10 having a lower hardness, the orifice member 100 can be heldreliably in position of the valve body 10. By making a taperedprojection 102 at or near the leading end of the orifice member 100 inthe press-fitting direction, more reliable joining is ensured.

Since the valve opening (valve seat) 104 of the orifice member 100 fordirect contact with the valve member is of stainless steel, it is freefrom corrosion due to erosion.

FIG. 4 shows a further embodiment of the invention.

This embodiment uses an orifice member 110 having a threaded outercircumferential surface 116. The orifice member 110 is fixed to thevalve body 10 by screw engagement between the threaded outer surface 116and a threaded portion formed in the valve body 10. Here again, theorifice member 110 has a tapered projection 112 near its leading end formore reliable joining. To facilitate the screw engagement, the orificemember 110 has a hexagon nut surface 118 on its outer circumference.

Also in this embodiment, since the orifice member 110 is made ofstainless steel, its valve opening 114 is free from damage by erosion.

FIG. 5 shows a still further embodiment of the invention.

The orifice member 120 used in this embodiment has a threaded outercircumferential surface 126 and a hexagonal bore 128 for engagement witha hexagon wrench. By inserting a hexagon wrench in the hexagonal bore128 of the orifice member 120, the orifice member 120 is affixed throughscrew engagement with the threaded portion of the valve body 10. Hereagain, the orifice member 120 has a tapered projection near its leadingend for more reliable joining.

Since the orifice member 120 is made of stainless steel, its valveopening 124 is free from damage by erosion.

FIG. 7 is a cross-sectional view showing a further embodiment of theexpansion valve according to the invention, and FIG. 8 shows part ofFIG. 7 in an enlarged scale.

The expansion valve 200 has an inlet port 220, an outlet port 222, and avalve chamber 223 adjacent the inlet port 220, which are formed in thevalve body 210. Affixed in the valve chamber 233 is an orifice member260.

A liquid refrigerant is supplied to the inlet port 220, travels throughthe orifice member 260 while expanding its volume, and is sent to theevaporator (not shown here and in the successive drawings) through theoutlet port 222. The refrigerant exiting from the evaporator isintroduced into a path 230 formed in the valve body 210. Exposed in thepath 230 is a heat-sensitive stem 240 whose upper end is connected to adiaphragm 242.

The lower end of the stem 240 extends through and beyond the orifice ofthe orifice member 260, and a valve member 244 is fixed to the lowerend. The valve member 244 is spherical and supported on a support member250.

The support member 250 is held on a cap 252 via a spring 254. The cap252 engages with a threaded portion 256 of the valve body 210 such thatthe depth of the screw engagement can be changed to adjust the force ofthe spring 254. The cap 252 has a hexagonal bore 253 for engagement witha wrench for such adjustment.

The orifice member 260 is affixed to the valve body 210 by screwengagement through a threaded portion 266 formed on its outercircumference. The orifice member 260 has a valve seat 262 and a hollowhexagonal bore 264. By using a wrench inserted in the hexagonal bore264, the orifice member 260 is joined to the valve body 210. The orificemember 260 has a projection 280 to bite into the valve body 210 forreliable joining.

By making the valve body 210 of brass and the orifice member 260 ofstainless steel or other like material, the corrosion resistance of theorifice portion can be improved.

FIG. 9 is a cross-sectional view showing a further embodiment of theexpansion valve according to the invention, and FIG. 10 shows part ofFIG. 9 in an enlarged scale.

The expansion valve 300 has a inlet port 320, outlet port 322, and valvechamber 323 adjacent the inlet port, which are formed in the valve body310. Affixed in the valve chamber 323 is an orifice member 360.

A liquid refrigerant is supplied to the inlet port 320, then travelsthrough the orifice member 360 while expanding its volume, and is sentto the evaporator through the outlet port 322. The evaporator contains aso-called heat-sensitive cylinder (not shown), and supplies a gaspressure onto a diaphragm 342 through a capillary 346. The gas pressureof the refrigerant at the outlet of the evaporator is supplied to thelower side of the diaphragm 342 through a pipe 348. A stem 340 connectedto the diaphragm 342 has a lower end extending through and beyond theorifice of the orifice member 360, and a valve member 344 is fixed tothe lower end of the stem 340. The valve member 344 is spherical andsupported on a support member 350.

The support member 350 is held on a cap 352 via a spring 354. The cap352 is mounted to the valve body 310 by engagement with a threadedportion 356 of the valve body 310 such that the depth of the screwengagement of the cap 352 can be changed to adjust the force of thespring 354. The cap 352 has a hexagonal bore 353 for receiving a wrenchfor such adjustment.

The orifice member 360 is joined to the valve body 310 by screwengagement of a threaded portion 366 on its outer circumference. Theorifice member 360 has a valve seat and a hollow hexagonal bore 364. Byusing a wrench inserted in the hexagonal bore 364, the orifice member360 is joined to the valve body 310. The orifice member 360 has aprojection 370 near its leading end to bite into the valve body 310 forreliable joining.

By making the valve body 310 of brass and the orifice member 360 ofstainless steel or other like material, the corrosion resistance of theorifice portion can be improved.

FIG. 11 is a cross-sectional view showing a further embodiment of theexpansion valve according to the invention, and FIG. 12 shows part ofFIG. 2 in an enlarged scale.

The expansion valve 400 has an inlet port 420, outlet port 422, andvalve chamber 423 adjacent the inlet port 420, which are formed in avalve body 410. Affixed in the valve chamber 423 is an orifice member460.

A liquid refrigerant is supplied to the inlet port 420, then travelsthrough the orifice member 460 while expanding its volume, and is sentto the evaporator through the outlet port 422. The evaporator contains aso-called heat-sensitive cylinder (not shown), and supplies a gaspressure onto the diaphragm 442 via the capillary 446. The diaphragm 442moves a valve support member 450 through a actuating rod 444.

A stem 452 attached to the support member 450 brings the spherical valvemember 454 in its opening and closing directions.

The support member 450 is held on a cap 470 via a spring 472. The cap470 is mounted to the valve body 410 by screw engagement with a threadedportion 474 of the valve body 410, such that the depth of the screwengagement of the cap 470 can be changed to adjust the force of thespring 472. The cap 470 has a hexagonal bore 476 for receiving a wrenchfor such adjustment.

The orifice member 460 is joined to the valve body 410 by screwengagement through a threaded portion 466 on its outer circumference.The orifice member 460 has a valve seat 462 and a hollow hexagonal bore464. By using a wrench inserted in the hexagonal bore 464, the orificemember 460 is joined to the valve body 410. The orifice member 460 has aprojection 468 near its leading end to bite into the valve body 410 forreliable joining.

By making the valve body 410 of brass and the orifice member 460 ofstainless steel or other like material, the corrosion resistance of theorifice portion can be improved.

FIG. 13 shows a further embodiment of the orifice member used in thepresent invention.

The orifice member 500 has a round orifice bore 502 in its center and athreaded portion 504 on its outer circumference. The orifice member 500has arcuate recesses 506 along its end surface to insert a tool in therecesses 506 and use it for joining the orifice member to the valvebody.

The means for engagement with a tool may be selected from variousconfigurations other than the arcuate recesses.

Although some embodiments have been explained as using stainless steelas the hard metallic material for the orifice member, the inventionenvisages the use of any metallic material having a Vickers hardnessranging from 150 to 500, such as aluminum bronze, nickel bronze,Stellite 6 (trademark), Stellite 6B (trademark), high-strength brassalloys (for example, HB91, a kind of metal called Hero Bronze marketedby Nippon Shindo Corporation), or the like. It is also possible toimprove the hardness of the valve opening by plating or surface-treatingthe valve opening portion of the valve body.

By incorporating any one of expansion valves described above in arefrigerating system, the life of the refrigerating can be elongatedeven when using an alternate flon-group refrigerant.

It should also be noted that, in a so-called electric expansion valve,its valve opening can be made of a metallic material having a highcorrosion resistance against a refrigerant comprising hydrogenoushalogenated hydrocarbon.

As described above, as a countermeasure against rotting caused byerosion at the valve opening because the valve body of an expansionvalve used in a refrigerating system is made of brass or other likematerial, considering the nature of a refrigerant used, the presentinvention makes the valve opening of a hard material to prevent erosion.More specifically, the hardness of the valve opening can be increased bylocal surface treatment, etc. Alternatively, by making an orifice memberof a hard material, the life of the expansion valve can be increased.

By using such an expansion valve, a long-life refrigerating system usingan alternate flon can be provided.

What is claimed is:
 1. An expansion valve comprising:a valve portionhaving a valve opening between an inlet path for introducing arefrigerant at a high pressure and an outlet path for letting out therefrigerant at a low pressure; a valve body which opens and closes thevalve opening; an orifice member having a valve seat which contacts thevalve body; wherein said orifice member is made of a metallic materialhaving a larger hardness than a hardness of the valve body, wherein saidorifice member is fixed to the valve body by screw means, and whereinsaid orifice member further comprises a projection which bites into thevalve body.
 2. The expansion valve according to claim 1, wherein saidmetallic material of said orifice member has a Vickers hardness rangingfrom 150 to
 500. 3. The expansion valve according to claim 2, whereinsaid metallic material is chosen from the group consisting of stainlesssteel, aluminum bronze, nickel bronze, Stellite, and high-strength brassalloys.
 4. The expansion valve according to claim 1, wherein saidrefrigerant is a non-chlorinated halogenated hydrocarbon refrigerant. 5.The expansion valve according to claim 1, wherein said orifice membercomprises a bore.
 6. The expansion valve according to claim 5, whereinsaid bore is hexagonal.